Under bed fumigator

ABSTRACT

Plastic mulched raised beds are fumigated using a fumigation system containing two opposing armatures affixed to a mounting arm at about a 50° angle and a blunt-ended knife with a blade attached at about a 90° angle to the knife. The system allows fumigant to be applied to the interior of the raised, plastic mulched beds without disturbing the mulch.

This is a divisional of application Ser. No. 10/263,107, filed Oct. 3,2002, which is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and method for fumigatingsoil under raised planting beds that are covered with plastic mulch.

2. Description of the Related Art

Soilborne pests and pathogens, including weed propagules, nematodes,insects, fungi, bacteria and certain other agents, can be limitingfactors in the production of crops. One of the principal strategies usedby growers of high-value horticultural crops to combat these organismsis to disinfest soil prior to planting, using pesticides or otherphysical or biological methods. Soil fumigants are the most effectivesoil disinfestation chemicals, and methyl bromide (MB) is the mostimportant soil fumigant chemical used by growers around the world. It isa broad-spectrum pesticide with excellent activity against mostpotential soil pests (Stapleton et al., California Agriculture, Vol. 54(6), 42–45, December 2000).

In production systems where polyethylene plastic is used as a mulch,preplant application of chemical fumigants is the principal methodemployed for control of soilborne pests. In Florida, for example,approximately 4.9 million Kg of methyl bromide were applied to 20,000 haof tomato (Lycopersicon esculentrum Mill.) during 1990 to controlsoilborne pests (Anonymous, USDA NAPIAP, April, 1993; Anonymous, Fla.Dep. Agric. Consum. Serv., 1993). Increased social and legislativepressure to restrict the use of chemical fumigants has created theimpetus to evaluate alternative approaches for management of soilbornediseases which minimize their impact.

Chellemi et al. (Plant Disease, Volume 78 (12) 1167–1172, December 1994)studied the effects of soil solarization using a photoselectivepolyethylene film, soil fumigation, and combinations of the two onsurvival of four soilborne plant pathogens in field plots in NorthernFlorida, and found that soil solarization alone resulted in asignificant decrease in the density of Phytophthora nicotianae andPseudomonas solanacearum down to a depth of about 25 and 15 cm.respectively. Significant reductions in the density of Fusariumoxysporum radicis-lycopersici and F.o lycopersici following soilsolarization occurred only in the upper 5 cm of soil. Fumigationsignificantly reduced populations of Phytophthora nicotianae,F.o.radicis-lycospersici, and F.o. lycopersici down to a depth of 35 cm.The effect of fumigation on P. solanacearum was highly variable.Additional reductions in the density of P. solanacearum were achievedwhen solarization was combined with fumigation. Synergistic effectsbetween soil solarization and chemical or organic amendments thatresulted in additional reductions of pathogen populations have beenobserved for other soilborne pests (Frank et al., Crop Prot., Vol. 5,199–202, 1986; Gamliel et al., Plant Dis., Vol. 77, 886–891, 1993;Gamliel et al, Phytopathology, Vol. 83, 899–905, 1993).

Various systems and apparatus have been devised for injecting chemicalfumigants into soil or spraying fumigants onto the soil surface and thensealing the fumigants using tarpaulins or foams. However, problemsassociated with fumigant emission from the soil have resulted in a lossof their effectiveness, disruption to the environment, and have posedheath risks to workers in the field.

Other methods for applying fumigants include drip irrigation, where awater soluble formulation is applied to soil with irrigation waterthrough the same irrigation systems that are later used to irrigate thecrops. The amount of water used to apply the fumigants, applicationrates, and soil conditions during application determine the success ofthese fumigants in controlling soil pathogens and weeds.

U.S. Pat. No. 3,640,234 (Carroll et al., Feb. 8, 1972) discloses afumigant injection apparatus which forms, fills and seals capsules ofvolatile fumigants at least 3 feet underground allowing the fumigant todiffuse through the soil and control pests and prevent fumigant escapeinto the atmosphere.

U.S. Pat. No. 3,964,405 (Haglund et al., Jun. 22, 1976) discloses theuse of spot penetration injectors, special furrowing equipment, andutilization of tooth or chisel applicators generally attached tocultivators to deeply place fumigants into the soil at about 14–24inches below ground level.

U.S. Pat. No. 6,167,821 (Beggs, Jan. 2, 2001) discloses a device forapplying fumigant below the surface of the soil and includes a soilleveling apparatus, and a soil packer. The apparatus further includes acover crop seed planter located behind the soil leveling apparatus. Thedevice includes a conventional fumigant applicator which is capable ofapplying fumigant to the soil at a depth of about 2 to 12 inches belowthe top surface of the soil. The fumigating portion of the deviceconsists of multiple chisel plows including an elongated tine with aconventional chisel tip. A stainless steel fumigant supply conduit witha spray nozzle at the end is connected to the tine so that the nozzle isapproximately halfway down the tine length. When the chisel is loweredto a depth of about 10 to 12 inches, the sprayer is at a depth of about4 to 8 inches allowing spray to reach the bottom of the chisel.

Miller et al.(Down to Earth, 18–20, Fall 1967) describe a soil injectionknife for applying fumigants to bedded land. The blade of the chiselknife is designed so that it sweeps down and back from the tool barforcing stalks and other crop debris down and off the tip of the bladeas it passes through the soil. The knives enter the side of a bed aboutthree inches above the bottom of the furrow. The tips of the knives areabout 12 inches apart during fumigant application. This requiresapproximately 15½ inches insertion into the bed. The tips of the bladesare then about 6 inches off center of the bed. Each knife contains drillholes for spraying fumigant.

While various methods and apparatus are used for applying fumigants tosoil, there remains a need for methods and apparatus for fumigationwhich inject fumigants under raised planting beds that have beenpreviously covered with plastic mulch. The present invention provides adevice for fumigation under existing raised, plastic-mulched bedswithout the use of drip irrigation which solves some of the problems ofthe prior art.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide afumigation system that will fumigate plastic mulched beds withoutdisturbing the plastic mulch or the soil profile.

A further object of the present invention is to provide a fumigationsystem that includes two opposing armatures that are adjustably attachedto the toolbar of a tractor and are adjustable to compensate for variousbed widths.

A still further object of the present invention is to provide afumigation system wherein each armature is attached to a mounting arm atabout a 15° angle from vertical.

A further object of the present invention is to provide a fumigationsystem having a knife comprising a contoured surface, a blunt tip, and ablade attached to said knife wherein said blade has an inner edge thatis a double kerf.

Another object of the present invention is to provide a method forfumigating plastic mulched beds comprising driving a tractor at a speeduseful for fumigating soil, wherein said tractor has attached to itstoolbar a pair of opposing armatures mounted at about a 15° angle onto amounting arm and the armatures further include a blunt-tipped knifecontaining a blade attached at about a 90° angle to said knife, whereinsaid knife and blade have a feed tube attached to the outer edge fordelivery of fumigant from a conduit attached to a fumigant containingtank mounted on said tractor.

A still further object of the present invention is to provide a methodfor fumigating plastic mulched beds wherein said fumigant is applied ata range of rates of about 8 gallons/acre to about 35 gallons/acre.

A further object of the present invention is to provide a method forfumigating including the step of applying fumigant to new plantings,existing crops, or additional crops planted in the same beds withoutdisturbing the soil profile.

Further objects and advantages of the present invention will becomeapparent from following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing showing the rear view of fumigation system 30including tractor 1, armatures 40, weights 15, toolbar 70, and mountingarm 24.

FIG. 2 is a drawing of an armature 40 showing mounting arm 24 includingmounting bracket 13 and support bracket 14, means for attaching 25,fumigant dispersal assembly 50, and close wheel assembly 60.

FIG. 3 is a drawing showing mounting detail including toolbar 70,mounting arm 24 including mounting bracket 13, support bracket 14, and15° angle of the armature.

FIG. 4 is a drawing showing the location of shim 20 in relation totoolbar 70 and armature 40, specifically shim 20, attachment plate 4 a,toolbar 70, and mounting strap 14 b.

FIG. 5 is a drawing of knife 22 showing contoured surface 22 a, bluntknife tip 22 b, knife bottom 22 e, rear facing edge 22 d, feed tube 26,blade 23, and double kerf 31.

FIG. 6 is a drawing of knife 22 showing a side view of knife 22 andblade 23 with feed tube 26.

FIG. 7 is a drawing of blade 23 showing inner tapered beveled edge 23 a,welded end 23 b, outer end 23 c, feed tube 26, and opening 26 a.

FIG. 8 is a graph showing the concentration of 1,3-dichloropropene, whenapplied in a mixture with chloropicrin (Telone C-35) at a rate of about35 gallons per acre (broadcast equivalent) under raised beds covered byLDPE (low density polyethylene) or VIF (virtually impermeable film)following application with fumigation system 30.

FIG. 9 is a graph showing survival of Fusarium oxysporum f. sp.lycopersici under different combinations of the fumigant Telone C35 (61%1,3-dichloropropene:35% chloropicrin), plastic film, and soilsolarization treatments using fumigation system 30. All clear filmsreceived about a 7-day soil solarization period prior to fumigation.

FIG. 10 is a graph showing emergence of nutsedge sprouts (Cyperus spp.)under different combinations of fumigant (Telone C35), plastic film, anda soil solarization treatment using fumigation system 30. All clearfilms received about a 7-day soil solarization period prior tofumigation.

FIG. 11 is a graph showing marketable yields of tomato (cv. Florida 47)under different combinations of fumigant (Telone C35), plastic films,and soil solarization using fumigation system 30. All clear filmsreceived about a 7-day soil solarization period prior to fumigation.

FIG. 12 is a graph showing marketable yields of pepper (cv. Enterprise)under different combinations of a fumigant (Telone C35), plastic film,and soil solarization using fumigation system 30. All clear filmsreceived about a 7-day soil solarization period prior to fumigation.

DETAILED DESCRIPTION OF THE INVENTION

Fumigation System 30 applies fumigants under existing planting beds thathave been covered by plastic mulch without disturbing their integrity,without damaging the plastic, and without using drip irrigation. Thepresent invention mitigates exposure of workers to chemical fumigantsand the impacts of manufacturer label restrictions requiring the use ofPersonal Protective Equipment (PPE) by workers present in the fieldduring fumigant application because it permits the fumigation process tobe separated from procedures required for preparation of the plantingbeds. It restricts the application of fumigants to the planting bed,reducing the overall quantity of fumigants applied to a field.Furthermore, the present invention improves the effectiveness offumigants by facilitating their use with virtually-impermeable filmsand/or a pre-soil solarization treatment.

Soil fumigation is a critical component of high value horticulturalcrops cultivated on raised, plastic-mulched planting beds.Traditionally, fumigants are shank injected into fields in advance ofbed preparation procedures (broadcast fumigation), shank injected intoplanting beds as they are being prepared (bed fumigation), or injectedthrough drip irrigation systems after beds have been prepared (dripirrigation).

While effective, broadcast fumigation is not practical for growersneeding to fumigate established plastic-mulched beds prior to their usefor a second (double) crop. Broadcast fumigation increases fumigant usebecause entire fields are treated including the row middles where cropsare not cultivated. Rapid emission of soil-applied fumigants into theatmosphere can cause environmental problems, prompting furtherrestrictions on their use. For example, high concentrations of thefumigant 1,3-dichloropene in the air near fumigated fields prompted afour-year suspension of its use in California in 1990.

During bed fumigation, workers are required in the field to assist withpreparation of planting beds. Several fumigant manufacturers requireworkers to wear personal protective equipment (PPE) includingchemical-resistant gloves, footware, coveralls, socks, and a respiratorwith an organic-vapor-removing cartridge. Logistical and economicconstraints associated with outfitting hundreds of workers with PPE andthe potential for heat related illnesses caused by their use in thesummer months make conventional bed fumigation undesirable for fumigantswith PPE restrictions.

Application of fumigants under virtually impermeable films (VIF) orfollowing a soil solarization treatment has been shown to significantlyimprove their effectiveness. A presolarization treatment is notcompatible with broadcast fumigation or bed fumigation.

Injection of fumigants through drip irrigation systems has been shown tobe effective. However, many growers do not have access to dripirrigation systems. For example, approximately 50 percent of the 59,400acres of fresh market tomato and pepper produced in Florida underfumigated soil are not drip irrigated and thus cannot access thistechnology.

Therefore, there is a need to deliver fumigants to the interior ofraised, plastic mulched beds without disturbing the integrity of thebeds and in a manner that is compatible with the use of a presoilsolarization and/or virtually impermeable films (VIF) and not dependantupon the presence of a drip irrigation system.

The following detailed description is based on modification of a Yetter30″ Avenger deep placement coulter system as a model system. However,given the following detailed description, one of ordinary skill in theart could readily modify any deep placement coulter system to practicethe claimed invention. It is also easily adaptable to fit variousplanting configurations and cropping requirements.

Fumigation system 30 includes tractor 1, a fumigant tank (not shown),down-pressure weights 15, toolbar 70, and two opposing armature systems40 for injecting fumigant into both sides of a mulched planting bedsimultaneously (FIG. 1). Each armature system 40 includes a main armassembly 4, hub and spindle assembly 10, a close wheel assembly 60, anda fumigant dispersal assembly 50 (FIG. 2). Each armature system 40 isadjustably mounted to toolbar 70 at an angle which allows maximumfumigation under a planting bed (FIGS. 2 and 3). An angle of about 10°to about 20° facilitates optimum fumigant injection and less stress toinjection blade 23. An angle greater than about 20° will cause moredisturbance of the plastic mulch and more stress on the hub and spindleassembly 10. An angle less than about 10° will cause fumigation outsidethe bed zone. Vertical mounting at a 0° angle does not allow thefumigant or injection blade 23 to reach up into the bed, resulting inmovement of the fumigant into the row middle. Also, vertical mountingresults in a horizantal position of fumigant injection blade 23,subjecting it to extreme stress from the resistance at the soil as it isdragged through the field, increasing the potential for bending orbreakage of blade 23. A preferred angle is about 15° Weights 15 aremounted on the tractor to facilitate penetration of blade 23 into theground so that the plastic mulch is not disturbed and fumigant isapplied at the desired depth. Up to about 500 pounds of weight percoulter blade 9 can be added to the tractor to achieve desired depth forfumigant application.

Main arm assembly 4 is any arm assembly of a coulter system. Main Armassembly 4 is modified by permanently attaching, such as by welding, ameans for attaching a coulter arm assembly, such as for example anattachment plate 4 a of arm assembly 4, to mounting bracket 13 ofmounting arm 24 at about a 10° to about a 20° angle, 15° preferable,from vertical to improve fumigant movement, increase wing angle (theangle of blade 23), and reduce drag. Angles from about 10° to about 20°are useful for the present invention. Bracket 13 is permanently attachedto support bracket 14 by welding for example. Support bracket 14 isremovably attached to toolbar 70 using any means for removably attaching25 such as, for example, a square U-bolt. This allows armatures 40 to beadjusted to conform to beds of varying widths. Armatures 40 areremovably attached to toolbar 70 through mounting strap 14 b which islocated on one side of toolbar 70 and affixed to attachment plate 4 a,on the opposite side of toolbar 70, with bolts. Mounting bracket 13further includes a shim 20 placed between attachment plate 4 a of armassembly 4 and tool bar 70 to create about a 5° variation in thehorizontal direction of each armature 40 for a change in width of theknife slot (opening in soil created by coulter blade) and to reduce drag(FIG. 4). One of ordinary skill in the art could readily determine howto adjust the variation in horizontal direction of armature 40 to anydegree to change the width of the knife slot and to reduce drag for anysoil condition give the detailed description of the present invention.Shim 20 is made of any non-compressible material, preferably flat steel,of about ⅛×1½×9 inches. One of ordinary skill in the art could readilydetermine the size of shim 20 to achieve the desired variation in thehorizontal direction of armature 40.

Fumigant dispersal assembly 30 includes a fumigant tank, a conduit 28operatively connected to the tank, fitting 27 operatively connectingconduit 28 to feed tube 26 and feed tube 26. Assembly 30 furtherincludes knife 22 and blade 23. Knife 22 is removably attached to knifearm 6 using shims 12 as needed to align knife 22. Any means forattaching 25 such as, for example, bolts, is within the ordinary skillof the art. Knife 22 is adjusted to align behind blade 9 using shims 12.Knife 22 is adjusted left and right to make the tip of knife 22 close,about ⅛″ to coulter blade 9. Knife 22 is approximately 16 inches long,about 4.75 inches wide, has contoured surface 22 a which roughlyconforms to the arc of the circular perimeter of coulter blade 9, andhas blunt tip 22 b which allows trash to clear under knife 22 (FIG. 5).Knife 22 includes feed tube 26 which can be, for example, an ⅛″ 316stainless steel pipe, welded to the back edge of knife 22 and the outeredge of blade 23 to within about ¾″ from end of blade 23 (FIG. 6). Feedtube 26 bends 90° at point of knife 22 and blade 23 intersection aboutand runs to about ¾″ from end of knife 23. Tube 26 has an opening 26 aat its end of about ⅛″ diameter for fumigant dispersal. Fitting 27,located at the top of tube 26, allows frictional attachment of conduit28. Conduit 28 delivers fumigant from fumigant tank (not shown) and canbe any conduit which is non-reactive to the fumigant such as, forexample, heavy wall cross link poly hose. Conduit 28 extends fromfumigant tank out to armature 4, threads into attachment plate 4 a ofarmature 4, passes along the outside of arm assembly 4 and over knifearm 6 to fitting 27 (FIGS. 1 and 2). Knife 22 has an associated beveledfumigant injection blade 23 which is permanently attached to the innerside of knife 22 at about a 90° angle from knife 22 vertical, about oneinch from bottom 22 e. outer-facing edge of blade 23 is flush withrear-facing edge 22 d of knife 22 (FIG. 7). The inner edge 23 a of blade23 is tapered and beveled such that the welded end 23 b of blade 23 isapproximately 3.5 inches and the outer end 23 c is approximately 2inches. The bevel is an approximately ¾″ double kerf 31. Knife 22 andassociated blade 23 are constructed of steel, however, substitution ofother materials such as, for example, abrasion resistant steel, is wellwithin the ordinary skill in the art.

In operation, armatures 40 are removably attached to toolbar 70 oftractor 1 and adjusted for bed width. Conduit 28 is attached to fitting27 to supply fumigant from fumigant tank to feed tube 26. Tractor 1moves over raised, plastic-mulched beds at speeds useful for applyingfumigants at a depth of about 6 inches below the soil surface of the rowmiddle and about 3 inches towards the interior center of the bed. Thedistance towards the interior center of the bed is equal to the lengthof blade 23. The device is designed to operate at speeds of betweenabout 3 and about 5 miles per hour, with 4 miles per hour the preferredspeed. The knife extends under the bed and reaches up into the interiorof the bed to clear the plastic mulch that is tucked in the soil. Up toabout 500 pounds per blade 9 of weights can be added to get the desireddepth for fumigant application.

Throughout this application, various publications are referenced. Thedisclosures of these publications in their entireties are herebyincorporated by reference into this application in order to more fullydescribe the state of the art to which this invention pertains.

The following examples are intended to further illustrate the inventionand are not intended to limit the scope of the invention as defined bythe claims.

EXAMPLE 1

Fall 2001, at USDA, ARS Header Canal Research Farm located in St. LucieCounty, Fla., the soil fumigant Telone C35 (65% 1,3-D and 35%chloropicrin) was applied using fumigation system 30 of the presentinvention. The soil type was a Riviera fine sand (93% sand, 4% silt, and3% clay) with an organic matter content of less than about 2% and a pHof about 6.9. Application of the fumigant was evaluated in combinationwith low density, polyethylene (LDPE), virtually impermeable films(VIF), and/or a 7-day pre-soil solarization period (Table 1).

The white LDPE film was 1.2 mil in thickness, embossed, coextruded,white on black film and considered the industry standard. The clear andblack VIF were 1.4 mil thick (Hytibarrier flex, Klerks Plastic Co.). Theclear LDPE film was 1.2 mil in thickness and embossed.

Treatments were arranged in a randomized complete block design andreplicated four times. Each replicate plot was a single row, 100 feetlong. Rows were arranged on about 6 foot centers. Bed dimensions wereabout 32 inches wide and about 10 inches high. At about 7 days afterapplication the plastics were painted white with a latex based paint(Kool Grow, SunTec Paints). Twenty-five tomato (Florida 91) andtwenty-five pepper (Enterprise) seedlings were transplanted into thecenter of each replicate plot using about a 2 foot spacing. The cropswere maintained using standard production practices.

Concentrations of 1,3-D in the soil air spaces were measured using aGastec Model GV-100 gas sampling pump with #139 dichloroethylenedetector tubes (Gastec Corporation, Ayase-City, Japan). A 2× correctionfactor was used to adjust the tube reading for 1,3-dichloropropene.Samples were collected at about 8-inch increments across the beds androw middles at about 24, 48, and 72 hours after application. Survival ofFusarium oxysporum f.sp. lycopersici and Phytophthora capsici in the bedcenters was determined by burying bags containing innoculum at about a 2inch depth. The effect of the fumigant application on weed populations,soilborne diseases and plant parasitic nematodes was monitored over thecourse of the season. The effect of the fumigant application onmarketable yield was determined from multiple harvests.

Fumigation System 30 was able to apply Telone C35 underneath the raised,plastic mulched beds without disturbing the integrity of the beds. Thebeds remained intact for the duration of the growing season, indicatingno disruption of their internal structure. Applications were made at atractor speed of about 4 miles per hour, which is consideredsatisfactory for pesticide application. No physical wear was observed onany components of the system during or after the experiment, indicatingthe durability of the device. Under the VIF, concentrations of Telone(1,3-D) reached a maximum of about 180 ppm at about 48 hours afterapplication (FIG. 8). This concentration is well above levels needed foreffective control of several key plant pathogenic fungi and nematodes.Concentrations of Telone C35 under the LDPE film remained less than 12ppm, an indication of the relative permeability of LDPE to the diffusionof 1,3-D into the atmosphere.

Survival of F.o. lycopersici was significantly reduced when fumigantapplications were combined with VIF or a 7-day pre-soil solarizationperiod (FIG. 9). The number of yellow and purple nutsedge sprouts thatemerged through the plastic mulch was significantly reduced by theTelone C35 applications even under the LDPE film (FIG. 10). Marketableyield of tomato was highest in treatments where fumigants were appliedunder VIF or following a 7 day pre-soil solarization treatment (FIG. 11,Table 2). The same general trend was observed for pepper yields (FIG.12, Table 2).

TABLE 1 Treatments Telone C35 Solarization Treatment Plastic rate *Timing Treatment 1 clear, LDPE **  0 gal/A — 7 days 2 clear, LDPE 35gal/A 7 day delay none 3 clear, VIF  0 gal/A — none 4 clear, VIF 35gal/A 7 day delay 7 days 5 white, LDPE  0 gal/A — 7 days 6 white, LDPE35 gal/A at bed formation none 7 black, VIF 35 gal/A 7 day delay none 8black, VIF 35 gal/A at bed formation none * broadcast acre rate ** LDPE= ; low density polyethylene film, VIF = virtually impermeable film

TABLE 2 Market Yield After Three Harvests Pepper Tomato Treatment(Plastic + Fumigant) lbs/plant boxes/acre * lbs/plant boxes/acre * ClearLDPE 3.1a 477 8.1ab 1260 Clear LDPE + Telone C35 ** 3.6a 522 9.7bc 1508Clear VIF 3.1a 486 9.0abc 1340 Clear VIF + Telone C35 ** 4.3a 665 10.3c1598 White/Black LDPE 2.9a 452 7.8a 1215 White/Black LDPE + Telone 3.0a465 7.9a 1222 C35 *** White/Black VIF + Telone C35 ** 3.6a 556 10.1c1569 White/Black VIF + Telone C35 *** 3.9a 601 8.9abc 1386 * Based on aplant density of about 4347 plants/acre (6 foot row spacing with 20 inchplant spacing. ** Telone C35 applied at about 35 gal/acre broadcast ratesame day as plastic *** Telone C35 applied at 35 gal/acre broadcast rate7 days after plastic application. Clear plastic painted white about 7days after plastic application. Means followed by the same letter arenot significantly different according to LSD (P = 0.10).

The foregoing detailed description is for the purpose of illustration.Such detail is solely for that purpose and those skilled in the art canmake variations therein without departing from the spirit an scope ofthe invention.

INDEX OF THE ELEMENTS

-   1. Tractor-   4. Main Arm Assembly-   4 a. Attachment Plate-   6. Knife Arm-   9. Coulter Blade-   10. Hub and Spindle Assembly-   12. Knife Shim-   13. Mounting Bracket-   14. Support Bracket-   14 b. Mounting Strap-   15. Weights-   20. Shim-   22. Knife-   22 a. Contoured Surface-   22 b. Blunt Tip-   22 d. Rear Facing Edge-   22 e. Knife Bottom-   23. Blade-   23 a. Inner Tapered, Beveled Edge-   23 b. Welded End-   23 c. Outer End-   23 d. Outer Facing Edge-   24. Mounting Arm-   25. Means for Attaching-   26. Feed Tube-   26 a. Opening-   27. Fitting-   28. Conduit-   30. Fumigation System-   31. Double Kerf-   40. Armature System-   50. Fumigant Dispersal Assembly-   60. Close Wheel Assembly-   70. Toolbar

1. A method for applying fumigant under plastic mulch planting bedscomprising: a. attaching two opposing armature system adjustably to atool bar of a tractor at an angle to permit fumigation of a plasticmulched planting bed without disturbing said plastic mulch wherein saidarmature systems include a main arm assembly, a hub and spindleassembly, a close wheel assembly and a fumigant dispersal assemblywherein said fumigant dispersal assembly includes a knife and blade, b.adjusting said armature system to plant bed width, c. operativelyattaching a fumigant tank to a blunt tipped knife having attached to itsinner side, at about a ninety degree angle, a beveled fumigant injectionblade; wherein said knife and blade include a feed tube with an openingfor fumigant dispersal, and d. moving said tractor over a raised,plastic mulched bed while applying fumigants under a plastic covering ofsaid raised, plastic mulched bed below a soil surface under said plasticcovering wherein said knife and blade inject fumigant into said soilfrom both sides of said bed.
 2. The method of claim 1 wherein saidarmature systems further include shims to vary horizantal direction ofsaid armature systems in order to vary knife slot width and reduce drag.3. A method for applying fumigant under plastic mulched planting bedscomprising: a. attaching two opposing armature systems adjustably to atool bar of a tractor at an angle to permit fumigation of a plasticmulched planting bed without disturbing said plastic mulch wherein saidarmature systems include shims to vary horizontal direction of saidarmatures in order to vary knife slot width and reduce drag, b.adjusting said armatures to plant bed width, c. operatively attaching afumigant tank to a blunt tipped knife having attached to its inner side,at about a ninety degree angle, a beveled fumigant injection blade;wherein said knife and blade include a feed tube with an opening forfumigant dispersal, and d. moving said tractor over raised, plasticmulched bed while applying fumigants below the soil surface to bothsides of said bed.